cmd/compile: remove gratuituous copying of lexer token data

Rename yySymType to lexer; should eventually capture all lexer state.
Embed lexer in parser and access lexer token data directly.

Change-Id: I246194705d594f80426f3ba77d8580af9185daf7
Reviewed-on: https://go-review.googlesource.com/19759
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

diff --git a/src/cmd/compile/internal/gc/lex.go b/src/cmd/compile/internal/gc/lex.go
index 08545df9538924e016f65966a8667afb2f7e2eee..a6f65bec624218a2b4a56b1e216060ff644fb855 100644 (file)
--- a/src/cmd/compile/internal/gc/lex.go
+++ b/src/cmd/compile/internal/gc/lex.go
@@ -866,10 +866,15 @@ func isfrog(c int) bool {
        return false
 }
 
-type yySymType struct {
-       sym *Sym
-       val Val
-       op  Op
+type lexer struct {
+       // TODO(gri) move other lexer state here and out of global variables
+       // (source, current line number, etc.)
+
+       // current token
+       tok  int32
+       sym_ *Sym // valid if tok == LNAME
+       val  Val  // valid if tok == LLITERAL
+       op   Op   // valid if tok == LASOP
 }
 
 const (
@@ -920,7 +925,7 @@ const (
        LRSH
 )
 
-func _yylex(yylval *yySymType) int32 {
+func (yylval *lexer) _yylex() int32 {
        var c1 int
        var op Op
        var escflag int
@@ -1402,7 +1407,7 @@ talph:
        if Debug['x'] != 0 {
                fmt.Printf("lex: %s %s\n", s, lexname(int(s.Lexical)))
        }
-       yylval.sym = s
+       yylval.sym_ = s
        return int32(s.Lexical)
 
 ncu:
@@ -1828,16 +1833,16 @@ func pragcgo(text string) {
        }
 }
 
-func yylex(yylval *yySymType) int32 {
-       lx := _yylex(yylval)
+func (l *lexer) next() {
+       tok := l._yylex()
 
-       if curio.nlsemi && lx == EOF {
+       if curio.nlsemi && tok == EOF {
                // Treat EOF as "end of line" for the purposes
                // of inserting a semicolon.
-               lx = ';'
+               tok = ';'
        }
 
-       switch lx {
+       switch tok {
        case LNAME,
                LLITERAL,
                LBREAK,
@@ -1855,7 +1860,7 @@ func yylex(yylval *yySymType) int32 {
                curio.nlsemi = false
        }
 
-       return lx
+       l.tok = tok
 }
 
 func getc() int {

diff --git a/src/cmd/compile/internal/gc/parser.go b/src/cmd/compile/internal/gc/parser.go
index 3a5b508393ddc353e9dcc5cfe82adb4582943ee9..deae40c21b653e97a64478b2ab64c8dd42747943 100644 (file)
--- a/src/cmd/compile/internal/gc/parser.go
+++ b/src/cmd/compile/internal/gc/parser.go
@@ -42,21 +42,10 @@ func parse_file(bin *obj.Biobuf) {
 }
 
 type parser struct {
-       tok    int32     // next token (one-token look-ahead)
-       op     Op        // valid if tok == LASOP
-       val    Val       // valid if tok == LLITERAL
-       sym_   *Sym      // valid if tok == LNAME
-       fnest  int       // function nesting level (for error handling)
-       xnest  int       // expression nesting level (for complit ambiguity resolution)
-       yy     yySymType // for temporary use by next
-       indent []byte    // tracing support
-}
-
-func (p *parser) next() {
-       p.tok = yylex(&p.yy)
-       p.op = p.yy.op
-       p.val = p.yy.val
-       p.sym_ = p.yy.sym
+       lexer
+       fnest  int    // function nesting level (for error handling)
+       xnest  int    // expression nesting level (for complit ambiguity resolution)
+       indent []byte // tracing support
 }
 
 func (p *parser) got(tok int32) bool {